Measurement of airway hyperresponsiveness: new considerations

Abstract

The term “airway responsiveness” is preferred when discussing PD₂₀ and PC₂₀ measurements as this is a non-specific term that encompasses the underlying mechanisms that may be responsible for differences in these measurements either between individuals or within an individual over time2. This is best illustrated in fig 1 where it can be seen that a decrease in PC₂₀ may be due to a steeper dose-response curve (hyperreactivity) or to a shift in the curve to the left (hypersensitivity), or both. Thus, when an individual displays a decreased PC₂₀ it is usually not known whether this is due to hyperreactivity or hypersensitivity although it is certainly one, the other, or both—all of which are covered by the term airway “hyperresponsiveness”.